A dog’s body is operated by hormones — hormones are chemical substances produced by glands and released in the blood to control different functions of the body. When the glands do not function properly, they overproduce or under-produce the hormones they make and upset normal body functions. This happens in the case of Cushing’s disease in dogs. Cushing’s disease is also referred to as Cushing’s syndrome. This is an overproduction of corticoid hormones in the adrenal glands and this is why it is also referred to as hyperadrenocoriticism.
If you understand the importance of these hormones in the body, then you will understand the problems your dog can face when things go wrong in these parts. The pituitary gland sits at the base of the brain and produces the adrenocorticotropic hormone (ACTH). ACTH stimulates the adrenal glands below that are situated just in front of the kidneys to produce the corticosteroid hormones – cortisol and cortisone.
These give the dog the “fight or flight” response to stress or dangers that present themselves. So for example, at the appearance of a bear in the neighbourhood, your dog immediately goes into flight mode because the adrenal hormones are released in him. Both the pituitary gland and the adrenal gland work hand in hand; the pituitary hormone stimulates the adrenal glands to produce corticosteroid hormones.
What goes wrong
When there is something wrong with either of these two glands, there will be an overproduction of the adrenal hormones cortisol and cortisone giving rise to Cushing syndrome. Cushing’s disease or hyperadrenocoriticism is caused from the malfunctioning of one or both of the glands in the body of the dog. The term Cushing’s disease is used because the condition was diagnosed in human early in the 1930s by Dr. Harvey Cushing.
There are two reasons for the adrenal glands to malfunction, giving rise to hyperadrenocoriticism. More often there is a tumor in the pituitary gland that causes it to release more ACTH hormone and further stimulates the adrenals to produce more cortisone. About 85% of dogs with Cushing’s disease is started from a tumor in the pituitary gland. This is usually referred to as Pituitary-dependent Cushing’s (PDC or PD). The other 15% of the disease is usually a result of a tumor in the adrenal glands and is termed Adrenal-dependent Cushing’s (ADH or AT).
The importance of Corticosteroid hormones
As you would find in any body function, too much or too little of anything will cause problems to develop in the body. The thing is that anything is possible. Corticosteroid hormones released in the blood by the adrenal glands are important for the maintenance of normal body functions. Understanding the importance of the hormones will help you understand their effects on the dog’s body system especially when they are not working in order.
- They regulate the amount of glucose in the blood and cause it to be stored by the liver. Too much glucose in the blood can cause diabetes.
- They maintain the dog’s immune system and where there is a malfunction, he becomes prone to diseases and infections.
- They help to regulate metabolism in the body, that is, the burning of calories.
- They are beneficial in bone growth and when produced in large amounts, can slow the absorption of calcium necessary for this to take place.
- When corticosteroid hormones are produced in too large a quantity, wounds take a longer time to heal.
- They are needed for proper brain function also and just as in humans, may be responsible for mood swings.
Dogs that are at risk
Cushing’s disease has affected all dog types. However, some dogs are more predisposed to develop the disease than others. Middle aged to older dogs, for example, have a greater likelihood of having it than younger dogs.
In both mixed breeds and purebreds, dogs are first diagnosed at an average age of 10.5 years. There are more incidences in females also than in males. Some breeds are also more susceptible to the disease, including, Terriers – Silkies, Yorkshire terriers, Bull terriers, and Boston terriers, Daschunds, Poodles, Beagles, American Eskimo dogs, Staffordshires, and Boxers.
Symptoms of Cushing’s disease
Cushing’s disease can present a variety of symptoms in your pet because of the diverse nature of the cortisol hormone. The symptoms however will be most noticeable at later stages of the disease. Early stage symptoms will gradually appear because of the slow growth of the tumors and vets may fail to diagnose it, or may misdiagnose it as other problems.
The more common symptoms include:
- Excessive thirst and increased urination. Diseased dogs drink from 2 – 10 times the amount of water they would normally have (PetEducation, 2015).
- Increased urination – This happens naturally as a consequence of the amount of water that the dog consumes. As an owner, you may find that you have to constantly fill up your pet’s container. The dog may therefore have accidents as he may not be able to get to the toilet on time as he fills up too quickly. In some cases the problem is mistaken for urinary tract disease.
- Weight gain and enlargements – Up to 80% of dogs experience an increase in appetite and subsequently gain weight due to the excess amount of cortisone that is produced by the adrenal glands (PetEducation, 2015). This happens even though their calorie intake is reduced. However you may even find that your dog is stealing food, rummaging in the garbage for more and being protective of his food. You may not see that there is a problem as you will consider his appetite to be good.
- Pot belly – Cushinoid dogs usually develop a pot belly as a result of fat shifting to the abdomen. This happens also because the liver enlarges and the muscles around the belly weaken. The liver is overworked trying to process all that cortisol hormone that is pushed into the body due to hyperadrenocorticism. As a result, the liver produces increased amounts of the enzyme alanine aminotransferase (ALT) and alkaline phosphatase (ALP). It is not uncommon therefore for Cushing’s disease to be misdiagnosed as a liver problem ((Mercola, 2015).
- Shrinking of muscles – One of the known facts and more perceptible sign is the shrinkage of muscles. You will notice that the dog’s feet get spindly and they are not able to bear his increased weight.
- Intense panting – You will find that your dog will pant more intensely. But this will be brought on by the pressure that is placed on his body systems due to the presence of the disease.
- Changes in the skin – Hair loss is a common problem in Cushing syndrome affected dogs occurring in 50% to 90% of cases. The hair will start to thin starting in those areas where there is more pressure on them, and will progress to the flank, abdomen and other areas (PetEducation, 2015). This is usually one of the first signs that will prompt you to take the dog to the vet. The dog will also experience thinning skin and easily bruises due to this. Wounds are hard to heal.
- Other signs – As a result of the effects on the immune system, the dog with Cushing may develop ear and urinary tract infections. Pets will become lethargic and not have interest in normal activities as before. His heavier weight will not allow him anyway.
Diagnosing Cushing syndrome in dogs
Considering your pet’s behavior — As you would observe, Cushing’s disease in dogs is quite diverse and therefore very complex to diagnose. It is a job of ruling out other health problems before even ruling in Cushing’s. In the first place you would have noticed certain behaviors in your pet to warrant a visit to the vet. Your dog may begin peeing the place, have extreme thirst and or exhibit hair loss that is not related to allergy or parasite infection.
Routine examination — The vet also will observe certain conditions as he detects an enlarged liver upon routine examination. Other things may pique his interest such as a previous infection that has returned or fails to heal. He may start to wonder why your pet’s urine is so dilute.
Laboratory tests — Even with all of these evidences, it is the results from laboratory tests that will tell that something is amiss. The vet will request some blood count and blood chemistry tests which very often will return high levels of liver enzymes – alkaline phosphatase, which is highly suggestive of Cushing’s disease. In many cases also, there is high cholesterol levels and an elevated blood sugar. It is common among Cushinoid pets to see low levels of thyroid hormones also (Hines, 2015).
Even with these findings that resemble results for Cushing’s, they are not enough to be definite that they are caused by the disease. These are also signs of many other diseases. However, as the dog owner you will discuss with your veterinarian the possibility of your dog developing Cushing’s disease or being in pre-Cushing state.
Urine Cortisol: creatinine ratio tests – To really get a definite diagnosis of Cushing’s syndrome the vet will need to order additional tests. It can be a complicated process and not something that is done quickly. More than one test may need to be carried out. In the first place, the doctor will seek to rule out other diseases. Secondly, he will seek to identify Cushing’s. Thirdly, he will determine where the disease is originating, whether in the pituitary gland (pituitary dependent Cushing), or the adrenal glands, (adrenal dependent Cushing). To demonstrate the complexity of trying to come up with a diagnosis, the vet may need to order two or more tests which when compared may not match.
One simple test that is done is determining the Urine Cortisol to Creatinine ratio, UC:Cr or UCC in the dog’s body. If the value of the UC:Cr ratio is normal, then it is likely that there is no Cushing’s. Abnormally high levels may suggest Cushing’s but a retest will need to be done since this is not so in some cases. In fact, only 1 in 4, or 5 dogs with abnormal urine cortisol to creatinine does have Cushing’s disease. Other health problems like heart disease, gastrointestinal problems, liver disease and stress can induce high UC:Cr ratio (Hines, 2015).
Low Dose Dexamethasone Suppression test (LDDs) – It is rather interesting how this test works. Dexamethasone is a compound that resembles dogs’ natural cortisone. When injected in the dog, its pituitary gland will send a message to the adrenal glands that there is enough cortisol and therefore they should not produce anymore. In normal cases, the cortisol level should be reduced. If there still remain high levels of cortisol in the body, it means that either the pituitary or the adrenal glands has tumor that is causing the production of cortisol. Most often this test differentiates Cushing disease from other health issues.
ACTH Stimulation test – This is a test that is commonly used and works similar to the Dexamethasone test. The dog’s pituitary gland produces ACTH that stimulates the production of adrenal cortisol hormones. When a synthetic form of ACTH is injected in the animal, more than the normal amount of cortisol will be produced. However, in a dog with Cushing’s, the level of cortisol will rise abnormally.
Ultrasound of the abdominals – Your vet may order an ultrasound of your pet’s belly. The ultrasound will examine the nature of the dog’s organs and show any abnormality such as the existence of a tumor, or if there is any enlargement. Pituitary dependent Cushing’s will show normal or abnormal adrenal glands, more than likely one is enlarged. This may suggest a tumor is lying there. The ultrasound will help to determine if the cancer has metastasize or spread to other organs of the body.
Other tests – Several other tests are available that will help to determine Cushing’s disease. The High Dose Dexamethasone Suppression test is done on the dog when Cushing’s disease is already determined but the location of the tumor is not. The test is similar to the LDDS. MRIs and CAT scan are two more invasive forms of imaging and are used to determine the location of tumors deep within tissues especially where they arevnot easily seen by the ultrasound.
Treating Cushing’s disease in dogs
There are two primary ways of management for dogs with Cushing’s disease. The small cell carcinomas and adrenal tumors can be treated through surgical intervention. This will require clearance from the veterinarian if the patient can be cleared for surgery because one of the most important considerations is overall health, and advancing age.
The surgery is not a very long procedure, but like any other invasive procedures, it will need such clearance to make sure that untoward reactions and complications are minimized. Most dogs are treated with medication, and many pet parents prefer this type of medical approach.
However, not all cases of Cushing’s disease can be treated with medication. There are some conditions that can only be controlled and corrected through surgery, while others need a combination of surgery and medication management. The veterinarian will be able to discuss the options with you to help the patient recover as soon as possible.
Several different oral medications are used in the treatment of Cushing’s.
Lysodren, otherwise called mitotane probably is still the most widely used drug in the treatment of Cushing’s disease. Vets are very careful in their use of the drug however, because of the serious side effects that it causes. Lysodren effectively acts like chemotherapy where it destroys the cortisol producing cells in the adrenal glands.
Close monitoring of the drug has to be done to determine if the condition is being reduced and your dog will be required to do repeat ACTH tests. Common side effects of Lysodren are diarrhea, vomiting, loss of appetite and lethargy due to the reduction in cortisol in his body.
This is a fairly newer drug but is as effective as Lysodren. It is also fairly milder on the dog producing fewer side effects. This drug should not be given if the dog has liver or kidney disorders, or if he may have been taking medication for heart problems. Like Lysodren, however, close monitoring has to be done by repeat ACTH tests to determine its effectiveness.
This drug works best if Cushing originates in the pituitary gland and not from adrenal tumors. The drug works by increasing the production of dopamine in the brain. Increased dopamine acts in the production of less ACTH in the pituitary, and ultimately generating smaller amounts of cortisol hormones in the adrenals.
Anipryl also causes less brutal side effects with only gastrointestinal upsets, disorientation, restlessness and sometimes hearing problems being experienced. However, the drug is seen to be effective in just 20% — 40% of cushinoid dogs (Hines).
This drug is not a first choice in the treatment of Cushing’s disease probably because improvements gained in using the drugs are not sustained. However, as an oral antifungal drug, it has average success and is used especially where other drugs are not successful.
Prognosis and life expectancy
Based on the general population of dogs affected with Cushing’s disease, the average life expectancy completely depends on how soon the condition was diagnosed, and where the issue originated. For cases that started in the adrenal gland, a good three to four years will be the life expectancy. However, dogs with pituitary gland issues can live for about two to three years. There are several factors that surround the actual life expectancy of the dog. Typically, the life expectancy is better when the dog is diagnosed at a younger age and earlier tumor development.
Aside from tumor identification, there are other health issues such as localized or systemic infection and diabetes can significantly reduce the life expectancy of the dog. Pituitary macro tumor syndrome or pulmonary thromboembolism might appear shortly after the initiation of treatment. Unfortunately, if this happens, some veterinarians will discuss options for further treatment, or in worst-case scenarios, euthanasia.
Generally speaking, the life expectancy of dogs with this condition will not experience the shortened life expectancy that much, especially for dogs that developed the disease during their later years where they have already enjoyed much about life.
Living with Cushing’s disease
There are some cases where a full recovery is not possible. This can be due to old age, and surgery is no longer a viable option. If your fur baby will be treated through a course of maintenance medications, you must be able to prepare that you will be doing the treatment until your dog lives. This requires patience, thorough understanding, and more love.
As a pet parent, your veterinarian will provide you with detailed instructions to help you with the medication schedule, and things to observe such as changes in behavior or physical appearance. A close collaboration is important to make sure that the quality of life of the affected dog is as comfortable as possible.
Stress is the number one factor that can aggravate the dog’s condition. You may want to re-evaluate the place where the dog rests, to promote a stress-free life as much as possible. You can openly discuss this with your veterinarian by presenting your current floorplan, including the potential hazards for vibration, excessive sounds, and guest visibility.
Once you re-organize your dog’s living space, you also detach him from the things that were part of his routine during his healthier days, considerably decreasing agitation and promoting a generally healthy and serene living space. This also works for other dogs that are already old, or puppies in the family that are too young.
The veterinarian will provide you with a schedule for routine follow-up visits, especially during the first few weeks. If your dog will be prescribed with medications such as mitotane, a scheduled follow-up every week is important to help the veterinarian assess the response of the dog’s body and the involved tumors if the initial doses are hitting the desired effect.
After a month, there will be an evaluation on the dose adjustment, as well as the frequency of visits. If the patient is already stable, the return visit will be modified once per month into once every quarter and eventually twice a year.
Bear in mind that Cushing’s disease is not a very debilitating condition. It is very important to remember that dogs with Cushing’s disease are quite challenging during the autumn to winter months, due to their inability to regulate their temperatures properly. Physical activities can be reduced depending on the severity of the condition. You can still live the normal routine with select reduction and modification.
There are some pet parents that get confused with the decrease in the organ capacity and advancing age. Both are somewhat correlated, but not completely the same. Almost all of the Cushing’s disease cases need preliminary diagnosis. Most cases will need treatment, while others only need supportive therapy and short-term management.
There are new discoveries that present themselves in the world of veterinary. In conditions such as Cushing’s disease, researches in both pharmacologic and surgical are in a constant improvement to help both affected dogs and their pet parents to have a better living condition and not let the disease hinder their daily lives. One pet expert explained that while this is in the process, it is very important to choose a veterinarian that jives with your pet parent philosophy because that will be easy for you when the time comes that treatment options would be explained in detail.
Different cases of Cushing’s disease that are not treated may progress to liver, kidney, heart, pancreatic, and neurological problems. It is a general knowledge that most metabolic illnesses will affect other organs. The rate Cushing’s disease affects a dog varies on a case-to-case basis. Most tumors grow very slowly, while there are isolated cases that progress at a very rapid rate. Usually, the progression of the disease can be evaluated on how the personality and behavior changes within the course of six to eight months after the initial diagnosis.
This rate will provide you with a quite clear picture on the progression curve of the dog’s illness. In addition, how the dog’s body responds to treatment will also be part of your observation and consideration in assessing the progression of the disease.
Increased cortisol levels in the blood makes dogs with Cushing’s disease more prone to infections. Extra attention is needed, as well as low-stress, proper nutrition, and somewhat monotonous life. The monotony can be alleviated by discussing this with your veterinarian. There is no treatment currently available in the market that offers a 100% reset like a brand new pooch. However, the available treatment protocols can provide effects that are as close as living a normal routine, which allows them to live more years that are comfortable and pain-free.
Notify the family
Having a dog with Cushing’s disease will lead the family to some major routine changes. One of the most noticeable change is the play and exercise routine. Dogs that have Cushing’s disease will have a significant reduction in activity, because of the rapid loss of energy and accelerated exhaustion. The family members should also be notified with the chances on diet, the addition of medications, and restrictions in activity.
It is very important to let every family member know what will change, and you may also include friends that frequent the house. Pet parents should also educate other family members that are not fully aware what the disease is all about that it is not contagious, and it is not harmful to the members of the family.
Recheck your routine
This is very applicable for pet parents that have more than one pet. Dogs with Cushing’s disease will need a little bit of extra on basically everything – nourishment, grooming, time, patience, budget, and attention. If you have more than one dog, do not let Cushing’s disease rob you from spreading your time with your other pets. They still need attention like any other pet, and you should not forget this. Make sure that they still receive their basic needs, as this avoids the formation of other health problems such as malnutrition, infection, and parasite infestation.
Cushing’s disease support groups
This condition is not uncommon, and you as a pet parent should not deal with it singlehandedly either. Due to the frequency of this disease, and the improvement of support groups available in cities and social networking sites, dealing with illnesses such as Cushing’s disease becomes easier. It promotes confidence, reassurance, and stories where you as a pet parent can totally relate. It can also be a go-to for situations on how to deal with daily problems.
There is just one things that you should not do when engaging with specialized support groups like these – you should not self-medicate your sick dog. Your veterinarian’s assessment should be your top priority. It is very important to follow his instructions because the dosages, frequency, and management will completely depend on the results of the preliminary and succeeding tests and specimen evaluation. Even if you think you are very sure that you are dealing with Cushing’s, you should never guess and jump into conclusion that you should buy the medications that you found on the internet.
What can you do?
Cushing’s disease in dogs is complex in its characteristics because of the organs that are affected. Most of all is the complexity in diagnosing the problem. There is so much care that has to be given in ensuring that Cushing’s is the problem and it is not other health issues that are affecting your dog. If Cushing disease is the diagnosis, be prepared that your dog may have to be on medication for the rest of its life.
It will be a journey that will demand your constant monitoring and that you maintain communication with your veterinarian. This way you will help to ensure a better quality of life for your dog than what would happen if not treated.
Cushing’s disease is one of the hurdles of being a pet parent, especially when they reach advancing age. However, as long as you are aware of what to do, and you have the right management, the right support system, and the right mindset, you will be able to appreciate life with your fur baby beyond the condition that you are dealing with.